FAILED: patch "[PATCH] fuse: nlookup missing decrement in fuse_direntplus_link" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.14.y
git checkout FETCH_HEAD
git cherry-pick -x b8bd342d50cbf606666488488f9fea374aceb2d5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023091602-untapped-scapegoat-dd85@gregkh' --subject-prefix 'PATCH 4.14.y' HEAD^..

Possible dependencies:

b8bd342d50cb ("fuse: nlookup missing decrement in fuse_direntplus_link") d123d8e1833c ("fuse: split out readdir.c")
63576c13bd17 ("fuse: fix initial parallel dirops")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b8bd342d50cbf606666488488f9fea374aceb2d5 Mon Sep 17 00:00:00 2001
From: ruanmeisi <[email protected]>
Date: Tue, 25 Apr 2023 19:13:54 +0800
Subject: [PATCH] fuse: nlookup missing decrement in fuse_direntplus_link

During our debugging of glusterfs, we found an Assertion failed error:
inode_lookup >= nlookup, which was caused by the nlookup value in the kernel being greater than that in the FUSE file system.

The issue was introduced by fuse_direntplus_link, where in the function, fuse_iget increments nlookup, and if d_splice_alias returns failure, fuse_direntplus_link returns failure without decrementing nlookup
https://github.com/gluster/glusterfs/pull/4081

index dc603479b30e..b3d498163f97 100644
@@ -243,8 +243,16 @@ static int fuse_direntplus_link(struct file *file,
 			dput(dentry);
 			dentry = alias;
 		}
-		if (IS_ERR(dentry))
+		if (IS_ERR(dentry)) {
+			if (!IS_ERR(inode)) {
+				struct fuse_inode *fi = get_fuse_inode(inode);
+
+				spin_lock(&fi->lock);
+				fi->nlookup--;
+				spin_unlock(&fi->lock);
+			}
 			return PTR_ERR(dentry);
+		}
 	}
 	if (fc->readdirplus_auto)
 		set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);